Gaseous conduction method and apparatus



June 21, 1932. c. cs. SMITH I GASEOUS CONDUCTION METHOD AND APPARATUSFiled April 12', 1926 n/fiwenzow amrz saaimwb WQAMWJ/ Patented June 21,1932 UNITED STATES PATENT OFFICE CHARLES G. SMITH, OF MEDFORD,MASSACHUSETTS, ASSIGNOR TO RAYTHEON INQ, OF CAMBRIDGE, MASSACHUSETTS, ACORPORATION OF MASSACHUSETTS GASEOUS CONDUCTION MET HOD AND APPARATUSApplication filed April 12,

In prior application Serial No. 7 6,7 94 filed December 21, 1925, isdescribed a gaseous conduction device having means for produclng ahighfrequency electrodeless ring discharge, thereby to reduce thevoltage drop by ionizing the gas between cathode and anode. According tothis invention improved results are obtained by producing ahigh-frequency discharge between electrode surfaces, one or both ofwhich may be auxiliary electrodes other than the main electrodes of thedevice.

The period of the high-fre uency discharge should be substantially conned to the time required for an electron to travel between said Theliberation of electrons at the electrode surfaces introduces complicatedphenomena involving factors of mobility,

mean free path, work function, etc. which ordinarily produce theso-called cathode drop, but by employing hi h frequencies according tothis invention a. g. 10 per second) the cathode drop effect issubstantially eliminated, presumably because the excursions of theositive ions are small (during each half-cySe) in com 'arison to themean free path of the ions. y virtue of the ionization produced by thehigh-frequency dish charge, preferably close to the cathode surface, thecathode-anode dischar e may be caused to assume arc characteristicswithout heating the cathode to temperatures ordinarily employed toproduce an are by thermiomc emission, probably for the reason that thenumber of positive ions falling at any instant u on the electrode issufiicient to account in arge measure for the currents flowing betweencathode and anode. Conseuently large current can be passed through t egaseous medium between the main electrodes with small applied voltages.The effect may be enhanced by confining the region surrounding theactive surface of the cathode to restrict radiation, as by making thecathode hollow and producing the highgequency discharge inside thehollow cath- For the purpose of illustrating the genus of the invention,reference may be had to the drawing in which Figure 1 is a view of oneembodiment of the invention; Figure 2 is a 1926. Serial No. 101,284.

re-entrant stem S of the housing H.- The gas contained in the housing ispreferably one which is readily ionizedand therefore for illustration adrop of mercury is shown at M to supply mercury vapor at a suitable Ipressure. If desired, other gases may be employed in the variousembodiments of the present invention, such as caesium, etc., asdisclosed in my prior applications.

In operation, the high-frequency discharge is produced between theplates K by means of high-frequency potential difference trans mittedthrough the transformer T. The resulting high-frequency current, whichmay ave a magnitude of the order of one-tenth ampere or more, ionizesthegas or vapor between the electrodes K, as evidenced by a glow in thespace between these electrodes, and as a result of this ionizationin-the region of the cathode surfaces the main discharge between thecathode surfaces and the anode A may be produced with a comparativelylow potential drop between the anode and cathode surfaces.

The embodiment shown in Fig. 2 is sim ilar to that shown in Fig. 1 andcorresponding parts are correspondingly designated.

However, the cathode is in the form of a hol-.

low box K which is approximately spherical.

This box has a discharge opening D opposite the anode, and at the bottomit has two cylindrical protuberances fitting over the insulat} ingsleeves I. The high-frequenc transformer T is connected to two rods andR spaced from each other within the hollow 1-; cathode, instead ofvbeing connected toth cathode surfaces as in Fig. 1. When ahighfrequency discharge is produced between the rods R and R the gaswithin the hollow cathode is ionized, thereby practically eliminatingthe cathode drop at the interior surface of the cathode, the maindischarge passing between the interior surface of the oathode and theanode through the opening D by virtue of the high state of ionizationinside the cathode. By confining the radiation generated inside thehollow cathode, the state of ionization may be enhanced and maintainedwith less loss of energy. Inasmuch as the ionized region is surroundedby the cathode K the latter serves to confine the radiation and theconservation of radiation may be still further effected in various waysas disclosed in my prior applications. For example, the loss ofradiation through the cathode K may be greatly reduced by making theinside surface of the cathode brightly reflecting. As in the case of theembodiment shown in Fig. 1, the form shown in Fig. 2 may employ anysuitable gas at the pressure best suited to the particular use for whichthe device is intended.

Obviously the invention may be applied in ways differing widely from thetwo embodiments chosen for the pur ose of illustration, and the claimsare there ore intended to be merely illustrated and not limited by thefigures.

I claim:

1. The method of producing a gaseous discharge having arccharacteristics between a cathode and an anode in a sealed vessel filledwith gas at substantial pressure, which comprises maintaining in thegaseous body adjacent said cathode an auxiliary high frequency dischargeof the order of one-tenth of an ampere and of a frequency of the orderof 100,000 cycles per second or more to ionize the gas adjacent thecathode and to impart to the discharge to the anode the character of anarc.

2. The method of producing a low voltage gaseous discharge between acathode aggregate comprising a pair of spaced electrodes and an anode ina discharge device having a sealed vessel filled with gas at substantialpressure, which comprises maintaining between said spaced electrodes anindependent high frequency discharge having a period confined to thetime required for an electron to travel between said spaced electrodes.

3. A unidirectional gaseous: conduction device comprising a sealedvessel containing a gas filling of substantial pressure, an anode acathode aggregate having an extended cathode surface, said cathode agegate having associated therewith a pair 0 spaced electrodes, means formaintaining between said pair of spaced electrodes a big}:) frequencyspace current ionizing the tween said electrodes to a degree at w 'ch adischarge having arc characteristics is produced between said anode andsaid cathode aggrecathode and an an gate, said cathode aggregateincluding means I constituting an enclosure around the gas adjacent thecathode surface between said spaced electrodes to conserve the energyand the ionization of the gas adjacent to, the cathode surface.

4. A unidirectional gaseous conduction decharacteristics is maintainedbetween said I cathode and said anode.

5. A unidirectional gaseous conduction device comprising a sealed vesselcontaining a gas filling of substantial pressure, an anode, a cathodeaggregate comprising a pair of spaced electrodes, and means formaintaining between said pair of spaced electrodes, a igh frequencyspace current ionizing the gas etween said electrodes to a degree atwhich a discharge having are characteristics is produced between saidanode and said cathode aggregate, the period of said high frequencyspace current being not larger than approximately the time necessary foran electron to travel under the applied voltage hetween the highfrequency discharge surfaces.

6. A unidirectionlal space current device com risin an enve 0 containinga gas, a

p g 05: spaced from each other within said envelo means adjacent saidcathode .enclosing a jacent the surface of said cathode a body ofionizable gas adapted to sustain a gaseous discharge, a pair of spacedelectrodes disposed in the enclosed space, and high uency inducing meansconnected to said pair of spaced-electrodes for producing in theenclosed gas a high frequency discharge ionizing said gas to provideelectric carriers for maintainin a discharge between said cathode .andsai anode having are characteristics.

Signed by me at Boston, Massachusetts,-

this 8th day of A ril 1926.

. LES G. SMITH.

